Induction of cell surface antigens on a lymphomatous cell line by gamma interferon

The interferons are known to induce the expression of cell surface determinants. Gamma interferon, in particular, has been shown to enhance class II antigens (DR) on the cell surface. We used this gamma interferon to induce beta 2-microglobulin (beta 2 mu) and a minor, sex related transplantation antigen called H-Y on the surface of B lymphoma cells. The antitumor effect of interferon could thus be at least twofold: an antiviral effect already known and an increase of intercellular recognition (by cell surface marker enhancement); allowing the tumor cells to be "seen" better by cells of the immune system.     

Formation of plastic connections of the visual system during ontogenesis of the rabbit

Analysis of evoked potentials and unit activity in the visual cortical projection area of rabbits revealed a definite succession of forming of interneuronal connections in ontogeny. In early postnatal period, the neuronal reactions were characterized by stable responses with one excitatory phase corresponding to initially negative surface evoked potential. Similarity of reactions of neurones situated in the same vertical column was observed and explained by functioning of a system of rigid connections of the thalamic relay nuclei afferents with cortical pyramidal neurones. Beginning from the third week of postnatal life of rabbits the neuronal reactions assumed a distinctly expressed phasic character, and variability of responses was seen along the vertical line. The changes revealed correlated with formation of a system of interneurones providing a possibility of plastic neuronal interaction. A study of the influence of preliminary cortical stimulation of the associative areas showed that intercentral cooperation mediated by cortical interneurones providing a systemic analysis of visual information began to form from the third week of postnatal life and reached the definitive level at later stages of development.     

Phytosociological characteristics of theRondeletio correifoliae-Andropogonetum multinervosi ass. nova (Sierra de la Siguanea,Isla de la Juventud,Cuba)

The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel.     

A specific high-performance liquid chromatography assay for dehydroascorbic acid shows an increased content in CLL lymphocytes

A method for the assay of dehydroascorbic acid using high-performance liquid chromatography with uv detection is described. The dehydroascorbic acid is separated from ascorbic acid and reduced with dithiothreitol, and is then quantitated as ascorbic acid following rechromatography. Since as little as 22 pmol can be detected, sensitivity is at least 40-fold greater than that of other currently available procedures. This method was used to measure the level of dehydroascorbic acid in normal and chronic lymphocytic leukemia lymphocytes. A significantly higher concentration of dehydroascorbic acid was found in leukemic (21.80 +/- 3.55 nmol/10(8) cells, mean +/- SE) than in normal lymphocytes (9.32 +/- 1.15 nmol/10(8) cells) (P less than 0.03). Analysis of extracts from normal B cell lymphocytes revealed comparable dehydroascorbic acid levels to unfractionated lymphocytes, indicating that the elevated level in chronic lymphocytic leukemia was not simply a reflection of the increased percentage of B lymphocytes in this disorder. These studies illustrate that the technique can be used to measure the dehydroascorbic acid content from sources where only scanty material is available or low levels are found.     

Ontogenetic analysis of the EEG-activation reaction in children

Frequency characteristics of EEG-reaction have been analysed in children of 3-10 years in the process of realization of the orienting reflex to sound stimuli. An enhancement of theta- and alpha-oscillations has been found in such conditions which becomes less pronounced to 9-10 years. In the last age group, the reaction of blockade of the basic rhythm of the background EEG (alpha-oscillations of 10 Hz) is formed, combined with local enhancement of other rhythmic components of this frequency range. Functional significance of different forms of EEG activation reaction has been determined. The question is discussed of functional heterogeneity of rhythmic components of the alpha-range and their differential involvement in the reaction reflecting complex mechanisms of cortical activation.     

Curing of the killer character of Saccharomyces cerevisiae with acridine orange

Acridine orange, an intercalating dye usually employed in the curing of bacterial plasmids, was tested for its ability to cure K1 and K2 killer strains (laboratory and wine strains). The results showed a high curing percentage of the killer character. This was demonstrated by the loss of M1 or M2 dsRNAs (responsible for toxin production and resistance to it) and because the meiotic products exhibited non-Mendelian segregation. The curing percentages varied, depending on the strain but not on the killer type, and showed similar efficiency as compared with other known curing agents.     

Mouse submandibular salivary epithelial cell growth and differentiation in long-term culture: Influence of the extracellular matrix

Summary The adult mouse submandibular salivary gland provides a good model system to study gene regulation during normal and abnormal cell behavior because it synthesizes functionally distinct products ranging from growth factors and digestive enzymes to factors of relevance to homeostatic mechanisms. The present study describes the long-term growth and differentiation of submandibular salivary epithelial cells from adult male mice as a function of the culture substratum. Using a two-step partial dissociation procedure, it was possible to enrich for ductal cells of the granular convoluted tubules, the site of epidermal growth factor synthesis. Long-term cell growth over a period of 2 to 3 mo. with at least 3 serial passages was obtained only within three-dimensional collagen gels. Cells grew as ductal-type structures, many of which generated lumens with time in culture. Electron microscopic analysis in reference to the submandibular gland in vivo revealed enrichment for and maintenance of morphologic features of granular convoluted tubule cells. Reactivity with a keratin-specific monoclonal antibody established the epithelial nature of the cells that grew within collagen. Maintenance of cell differentiation, using immunoreactivity for epidermal growth factor as criterion, was determined by both cytochemical and biochemical approaches and was found to be dependent on the collagen matrix and hormones. Greater than 50% of the cells in primary collagen cultures contained epidermal growth factor only in the presence of testosterone and triiodothyronine. In contrast, cells initially seeded on plastic or cycled to plastic from collagen gels were virtually negative for epidermal growth factor. Biochemical analysis confirmed the presence of a protein with an apparent molecular weight of 6000 which comigrated with purified mouse epidermal growth factor. Epidermal growth factor was also present in detectable levels in Passage 1 cells. This culture system should permit assessment of whether modulation of submandibular gland ductal cell growth can be exerted via a mechanism that in itself includes epidermal growth factor and its receptor and signal transduction pathway. This work was supported by Public Health Service grant DE07766 from the National Institute of Dental Research, National Institutes of Health, Bethesda, MD.     

Effects on breathing of rostral pons glutamate injection during opossum development

To determine whether pathways from the rostral pons, capable of influencing breathing, were present in immature mammals, the excitatory amino acid glutamate (sodium salt) was pressure injected in very small volumes into the rostral pons of suckling and adult opossums. The youngest animals tested were approximately 3 wk old (1.5-2.9 g). Animals were anesthetized with the thiobarbituric acid derivative, Inactin, and the electromyogram of the diaphragm was used to assess changes in breathing rhythm and ventilatory output. Glutamate concentrations of 50, 150, and 1,000 mM were injected into the rostral pons. Active sites were generally located between parabrachial and either lateral lemniscal or trigeminal nuclei. Effects of glutamate in opossums of all ages included changes in diaphragm activity and respiratory timing over several breaths. In the youngest animals, a very high incidence of apnea occurred as an initial response (17 of 20 sites) at the 1,000 mM concentration. The high incidence of apneic response in the youngest animals suggests that strong activation of rostral pontine neurons can more easily disrupt respiratory output; a physiological circumstance of such activation might include a diving response stimulated by trigeminal afferents.     

Adenylyl cyclase and G-proteins in Phytomonas

Phytomonas sp. membranes have an adenylyl cyclase activity which is greater in the presence of Mn2+ than with Mg2+. The Mg2+ and Mn2+ activity ratio varies from one membrane preparation to another, suggesting that the adenylyl cyclase has a variable activation state. A[35S]GTP-gamma-S-binding activity with a Kd of 171 nM was detected in Phytomonas membranes. Incubation of these membranes with activated cholera or pertussis toxin and [adenylate 23P]NAD+ led to incorporation of radioactivity into bands of about 40-44 kDa. Crude membranes were electrophoresed on SDS-polyacrylamide gels and analyzed, by Western blotting, with the 9188 anti-alpha[s] antibody and the AS/7 antibody (anti-alpha[i], anti-alpha[i1], and anti-alpha[i2]. These procedures resulted in the identification of polypeptides of approximately 40-44 kDa. Phytomonas adenylyl cyclase could be activated by treatment of membrane preparations with cholera toxin, in the presence of NAD+, while similar treatment with pertussis toxin did not affect this enzyme activity. These studies indicate that in Phytomonas, adenylyl cyclase activity is coupled to an unknown receptor entity through G alpha[s] proteins.